If lcm(a,b)=60\text{lcm}(a, b) = 60lcm(a,b)=60 and gcd(a,b)=4\gcd(a, b) = 4gcd(a,b)=4, which of the following could be a valid pair (a,b)(a, b)(a,b)?
(12,20)(12, 20)(12,20)
(4,60)(4, 60)(4,60)
(20,12)(20, 12)(20,12)
(15,16)(15, 16)(15,16)